[PATCH 27/29] iommu: exynos: document internal structures

[Marek Szyprowski]

Add a few words of comment to all internal structures used by the driver.

Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
 drivers/iommu/exynos-iommu.c | 59 ++++++++++++++++++++++++++++----------------
 1 file changed, 38 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 7600861..78ce618 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -189,37 +189,54 @@ static char *sysmmu_fault_name[SYSMMU_FAULTS_NUM] = {
 	"UNKNOWN FAULT"
 };
 
-/* attached to dev.archdata.iommu of the master device */
+/*
+ * This structure is attached to dev.archdata.iommu of the master device
+ * on device add, contains a list of SYSMMU controllers defined by device tree,
+ * which are bound to given master device. It is usually referenced by 'owner'
+ * pointer.
+ */
 struct exynos_iommu_owner {
-	struct list_head clients;
+	struct list_head clients; /* list of sysmmu_drvdata.owner_node */
 };
 
+/*
+ * This structure is stored in ->priv field of generic struct iommu_domain,
+ * contains list of SYSMMU controllers from all master devices, which has been
+ * attached to this domain and page tables of IO address space defined by this
+ * domain. It is usually referenced by 'domain' pointer.
+ */
 struct exynos_iommu_domain {
-	struct list_head clients; /* list of sysmmu_drvdata.node */
+	struct list_head clients; /* list of sysmmu_drvdata.domain_node */
 	sysmmu_pte_t *pgtable; /* lv1 page table, 16KB */
 	short *lv2entcnt; /* free lv2 entry counter for each section */
-	spinlock_t lock; /* lock for this structure */
+	spinlock_t lock; /* lock for modyfying list of clients */
 	spinlock_t pgtablelock; /* lock for modifying page table @ pgtable */
 };
 
+/*
+ * This structure hold all data of a single SYSMMU controller, this includes
+ * hw resources like registers and clocks, pointers and list nodes to connect
+ * it to all other structures, internal state and parameters read from device
+ * tree. It is usually referenced by 'data' pointer.
+ */
 struct sysmmu_drvdata {
-	struct device *sysmmu;	/* System MMU's device descriptor */
-	struct device *master;	/* Owner of system MMU */
-	void __iomem *sfrbase;
-	struct clk *clk;
-	struct clk *clk_master;
-	int activations;
-	int suspended;
-	spinlock_t lock;
-	struct iommu_domain *domain;
-	struct list_head domain_node;
-	struct list_head owner_node;
-	phys_addr_t pgtable;
-	int version;
-	const char *name;
-	dma_addr_t base;
-	size_t size;
-	struct notifier_block pm_notifier;
+	struct device *sysmmu; /* SYSMMU controller device */
+	struct device *master; /* master device (owner of given SYSMMU) */
+	void __iomem *sfrbase; /* our registers */
+	struct clk *clk; /* SYSMMU's clock */
+	struct clk *clk_master; /* master's device clock */
+	int activations; /* number of calls to sysmmu_enable */
+	int suspended; /* status of the controller (managed by runtime pm) */
+	spinlock_t lock; /* lock for modyfying enable/disable state */
+	struct iommu_domain *domain; /* domain we belong to */
+	struct list_head domain_node; /* node for domain clients list */
+	struct list_head owner_node; /* node for owner clients list */
+	phys_addr_t pgtable; /* assigned page table structure */
+	int version; /* our version */
+	const char *name; /* our name from device tree */
+	dma_addr_t base; /* base addres of IO address space define in DT */
+	size_t size; /* size of IO address space define in DT */
+	struct notifier_block pm_notifier; /* notifier for pm domain on/off */
 };
 
 static bool set_sysmmu_active(struct sysmmu_drvdata *data)
-- 
1.9.2

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